Adding Products in PowerStore2

Adding Products in PowerStore2

I am not a designer by far of websites, but I love to tinker with your products. I am using PowerStore 2 for my site. I have unsuccessfully attempted many times to add images and I get the following error:Fatal error: Call to undefined function imagecreatefrompng() in C:\inetpub\wwwroot\PowerStore\WA_DigitalFilePro\HelperPHP.php on line 840

Please help me understand where the file needs to be edited. Can you send me code (if needed) to add to line 840 to correct this error.